This is simply not true. Madison, WI just finished a massive revamp of their entire bus system where many existing routes were re-aligned or replaced with rapid transit routes with dedicated lanes. Despite massive amounts of naysaying from local conservatives the project has been a massive success and has resulted in a huge bump in ridership [1].
The whole thing happened because the city elected a mayor [2] who was laser focused on making transit happen and just kept working on it.
I think US politics has a major incentive alignment problem - if your local politician's genuine personal success metric is "improved transit" then you're likely to end up with improved transit. If success is "got re-elected", "got more corporate donations" or "used mayorship as a stepping stone to national politics" then you're likely to end up with a milquetoast compromiser who never does anything of substance because they don't want to be accountable for anything.
[1] https://www.channel3000.com/news/madison-metro-sees-brt-wind...